I heard that 10" subs are better for house and dance music and that 12" subs are better for rap. Is this true? Do 12" subs give as crisp a sound as 10" subs? Thanks.
Depends on your amplifier also. I would recommend 12...i think that is the best all-around size. it will pack quick and hard punch for both rap or dance music, as it is large enough to push sufficient air, yet small enough to quickly recover. I myself have dual 15 inch subs driven by 1000 watts PLUS dual stiffening capacitators, and for dance music i can STILL hear bass lag. but then, i don't usually listen to dance.
A good 12 will sound as "fast" as a comparable quality 10 any day. In general the size of the driver has more to do with how loud it can play rather then the SQ. There are plenty of 12 or 15 inch drivers that can sound better then a poorly made 10. The enclosure you put the driver in will make the biggest difference in sound.
Not to mention that a 12" will not have to displace as much air to produce a given SPL. So basically when a 10" driver is reaching it's limits, a 12" (same model) will retain more linearity.
Adire has a great article on how inductance plays the significant role in transient response as opposed to Mms.